Dialkyl carbonates (especially dimethyl carbonate) have found extensive use in the chemistry industry. With relatively gentle reaction conditions, high yield and co-production of glycols, the transesterification process has been valued as the most promising process in industry for producing dialkyl carbonates.
Generally, the transesterification reaction takes an alkali metal hydroxide, an alkali metal carbonate or an alkali metal alkoxylate as the catalyst, which are of homogeneous type and therefore are difficult to separate from the reaction products. A catalyst produced by supporting an alkali metal or alkali metal salt onto a carrier is vulnerable to water or CO2 in the air, which may decrease the catalyst activity significantly. Metal oxide type catalysts, alkali (earth) metal exchanged zeolite type catalysts or clay type catalysts suffer from a relatively low activity or selectivity. Ion exchange resin type catalysts like quaternary amine or tertiary amine based catalysts suffer from unstable catalyst activity since N elements contained therein is easily detachable after long-term use.
Therefore, there is still a need in the prior art for a catalyst for producing dialkyl carbonates, which can be produced by a simple and industrially favorable process, and with which, the aforesaid drawbacks in connection with the prior art catalysts can be effectively overcome.